Ceramic materials are especially advantageous in process technology, because they exhibit good media resistance and temperature stability. Furthermore, many ceramic materials have excellent elastic properties, so that they are applied, for example, for manufacturing pressure sensors. In the case of technical devices, it is often required to provide an electrical contact through a ceramic material, for example, in order to implement the electrical transducer of a pressure sensor. Electrical feedthroughs are produced, for example, by melted glass encasing of metal conductors, when the feedthroughs are to be implemented in metal housings. In the case of ceramic components, feedthroughs are implemented also by the soldering in of a metal conductor of the ceramic component. In such case, it is especially to be heeded, when a pressure sensor is involved, that the solder connection be mechanically strong, high vacuum tight and compatible with the other process steps of the manufacture of the pressure sensor containing the ceramic component.
In European Patent EP 0 414 872 B1, a pressure sensor is disclosed, in the case of which, in a ceramic body comprising aluminum oxide, metal conductors are secured with a silver-copper-, or a silver-copper-indium solder. For increasing reactivity, reactive elements, such as titanium, zirconium, beryllium or tantalum, are added to this solder. This solder proves to be disadvantageous, however, since the coefficients of thermal expansion of the solder and the aluminum oxide ceramic are not ideally matched to one another. Furthermore, the further manufacturing of the pressure sensor proves to be difficult, since the connecting of the measuring membrane of the pressure sensor with the platform of the pressure sensor requires a high temperature soldering process in vacuum, in the case of which a zirconium-nickel-titanium-active braze is used. The conductor in the bore through the platform, and, respectively, the measuring membrane, must be soldered in the same process. Insofar, the process parameters must be so selected that the two soldering processes, thus the joining of the measuring membrane with the platform and the soldering in of the conductor into the bores can occur synchronously. For this, there remains only a relatively narrow temperature range, which makes the process very complicated and error prone.